1 //#define DEBUG 2 #include <linux/spinlock.h> 3 #include <linux/slab.h> 4 #include <linux/blkdev.h> 5 #include <linux/hdreg.h> 6 #include <linux/virtio.h> 7 #include <linux/virtio_blk.h> 8 #include <linux/scatterlist.h> 9 #include <linux/string_helpers.h> 10 #include <scsi/scsi_cmnd.h> 11 12 #define PART_BITS 4 13 14 static int major, index; 15 struct workqueue_struct *virtblk_wq; 16 17 struct virtio_blk 18 { 19 spinlock_t lock; 20 21 struct virtio_device *vdev; 22 struct virtqueue *vq; 23 24 /* The disk structure for the kernel. */ 25 struct gendisk *disk; 26 27 /* Request tracking. */ 28 struct list_head reqs; 29 30 mempool_t *pool; 31 32 /* Process context for config space updates */ 33 struct work_struct config_work; 34 35 /* What host tells us, plus 2 for header & tailer. */ 36 unsigned int sg_elems; 37 38 /* Scatterlist: can be too big for stack. */ 39 struct scatterlist sg[/*sg_elems*/]; 40 }; 41 42 struct virtblk_req 43 { 44 struct list_head list; 45 struct request *req; 46 struct virtio_blk_outhdr out_hdr; 47 struct virtio_scsi_inhdr in_hdr; 48 u8 status; 49 }; 50 51 static void blk_done(struct virtqueue *vq) 52 { 53 struct virtio_blk *vblk = vq->vdev->priv; 54 struct virtblk_req *vbr; 55 unsigned int len; 56 unsigned long flags; 57 58 spin_lock_irqsave(&vblk->lock, flags); 59 while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) { 60 int error; 61 62 switch (vbr->status) { 63 case VIRTIO_BLK_S_OK: 64 error = 0; 65 break; 66 case VIRTIO_BLK_S_UNSUPP: 67 error = -ENOTTY; 68 break; 69 default: 70 error = -EIO; 71 break; 72 } 73 74 switch (vbr->req->cmd_type) { 75 case REQ_TYPE_BLOCK_PC: 76 vbr->req->resid_len = vbr->in_hdr.residual; 77 vbr->req->sense_len = vbr->in_hdr.sense_len; 78 vbr->req->errors = vbr->in_hdr.errors; 79 break; 80 case REQ_TYPE_SPECIAL: 81 vbr->req->errors = (error != 0); 82 break; 83 default: 84 break; 85 } 86 87 __blk_end_request_all(vbr->req, error); 88 list_del(&vbr->list); 89 mempool_free(vbr, vblk->pool); 90 } 91 /* In case queue is stopped waiting for more buffers. */ 92 blk_start_queue(vblk->disk->queue); 93 spin_unlock_irqrestore(&vblk->lock, flags); 94 } 95 96 static bool do_req(struct request_queue *q, struct virtio_blk *vblk, 97 struct request *req) 98 { 99 unsigned long num, out = 0, in = 0; 100 struct virtblk_req *vbr; 101 102 vbr = mempool_alloc(vblk->pool, GFP_ATOMIC); 103 if (!vbr) 104 /* When another request finishes we'll try again. */ 105 return false; 106 107 vbr->req = req; 108 109 if (req->cmd_flags & REQ_FLUSH) { 110 vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH; 111 vbr->out_hdr.sector = 0; 112 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 113 } else { 114 switch (req->cmd_type) { 115 case REQ_TYPE_FS: 116 vbr->out_hdr.type = 0; 117 vbr->out_hdr.sector = blk_rq_pos(vbr->req); 118 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 119 break; 120 case REQ_TYPE_BLOCK_PC: 121 vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD; 122 vbr->out_hdr.sector = 0; 123 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 124 break; 125 case REQ_TYPE_SPECIAL: 126 vbr->out_hdr.type = VIRTIO_BLK_T_GET_ID; 127 vbr->out_hdr.sector = 0; 128 vbr->out_hdr.ioprio = req_get_ioprio(vbr->req); 129 break; 130 default: 131 /* We don't put anything else in the queue. */ 132 BUG(); 133 } 134 } 135 136 sg_set_buf(&vblk->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr)); 137 138 /* 139 * If this is a packet command we need a couple of additional headers. 140 * Behind the normal outhdr we put a segment with the scsi command 141 * block, and before the normal inhdr we put the sense data and the 142 * inhdr with additional status information before the normal inhdr. 143 */ 144 if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC) 145 sg_set_buf(&vblk->sg[out++], vbr->req->cmd, vbr->req->cmd_len); 146 147 num = blk_rq_map_sg(q, vbr->req, vblk->sg + out); 148 149 if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC) { 150 sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense, SCSI_SENSE_BUFFERSIZE); 151 sg_set_buf(&vblk->sg[num + out + in++], &vbr->in_hdr, 152 sizeof(vbr->in_hdr)); 153 } 154 155 sg_set_buf(&vblk->sg[num + out + in++], &vbr->status, 156 sizeof(vbr->status)); 157 158 if (num) { 159 if (rq_data_dir(vbr->req) == WRITE) { 160 vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; 161 out += num; 162 } else { 163 vbr->out_hdr.type |= VIRTIO_BLK_T_IN; 164 in += num; 165 } 166 } 167 168 if (virtqueue_add_buf(vblk->vq, vblk->sg, out, in, vbr) < 0) { 169 mempool_free(vbr, vblk->pool); 170 return false; 171 } 172 173 list_add_tail(&vbr->list, &vblk->reqs); 174 return true; 175 } 176 177 static void do_virtblk_request(struct request_queue *q) 178 { 179 struct virtio_blk *vblk = q->queuedata; 180 struct request *req; 181 unsigned int issued = 0; 182 183 while ((req = blk_peek_request(q)) != NULL) { 184 BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems); 185 186 /* If this request fails, stop queue and wait for something to 187 finish to restart it. */ 188 if (!do_req(q, vblk, req)) { 189 blk_stop_queue(q); 190 break; 191 } 192 blk_start_request(req); 193 issued++; 194 } 195 196 if (issued) 197 virtqueue_kick(vblk->vq); 198 } 199 200 /* return id (s/n) string for *disk to *id_str 201 */ 202 static int virtblk_get_id(struct gendisk *disk, char *id_str) 203 { 204 struct virtio_blk *vblk = disk->private_data; 205 struct request *req; 206 struct bio *bio; 207 int err; 208 209 bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES, 210 GFP_KERNEL); 211 if (IS_ERR(bio)) 212 return PTR_ERR(bio); 213 214 req = blk_make_request(vblk->disk->queue, bio, GFP_KERNEL); 215 if (IS_ERR(req)) { 216 bio_put(bio); 217 return PTR_ERR(req); 218 } 219 220 req->cmd_type = REQ_TYPE_SPECIAL; 221 err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false); 222 blk_put_request(req); 223 224 return err; 225 } 226 227 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode, 228 unsigned int cmd, unsigned long data) 229 { 230 struct gendisk *disk = bdev->bd_disk; 231 struct virtio_blk *vblk = disk->private_data; 232 233 /* 234 * Only allow the generic SCSI ioctls if the host can support it. 235 */ 236 if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_SCSI)) 237 return -ENOTTY; 238 239 return scsi_cmd_ioctl(disk->queue, disk, mode, cmd, 240 (void __user *)data); 241 } 242 243 /* We provide getgeo only to please some old bootloader/partitioning tools */ 244 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) 245 { 246 struct virtio_blk *vblk = bd->bd_disk->private_data; 247 struct virtio_blk_geometry vgeo; 248 int err; 249 250 /* see if the host passed in geometry config */ 251 err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY, 252 offsetof(struct virtio_blk_config, geometry), 253 &vgeo); 254 255 if (!err) { 256 geo->heads = vgeo.heads; 257 geo->sectors = vgeo.sectors; 258 geo->cylinders = vgeo.cylinders; 259 } else { 260 /* some standard values, similar to sd */ 261 geo->heads = 1 << 6; 262 geo->sectors = 1 << 5; 263 geo->cylinders = get_capacity(bd->bd_disk) >> 11; 264 } 265 return 0; 266 } 267 268 static const struct block_device_operations virtblk_fops = { 269 .ioctl = virtblk_ioctl, 270 .owner = THIS_MODULE, 271 .getgeo = virtblk_getgeo, 272 }; 273 274 static int index_to_minor(int index) 275 { 276 return index << PART_BITS; 277 } 278 279 static ssize_t virtblk_serial_show(struct device *dev, 280 struct device_attribute *attr, char *buf) 281 { 282 struct gendisk *disk = dev_to_disk(dev); 283 int err; 284 285 /* sysfs gives us a PAGE_SIZE buffer */ 286 BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES); 287 288 buf[VIRTIO_BLK_ID_BYTES] = '\0'; 289 err = virtblk_get_id(disk, buf); 290 if (!err) 291 return strlen(buf); 292 293 if (err == -EIO) /* Unsupported? Make it empty. */ 294 return 0; 295 296 return err; 297 } 298 DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL); 299 300 static void virtblk_config_changed_work(struct work_struct *work) 301 { 302 struct virtio_blk *vblk = 303 container_of(work, struct virtio_blk, config_work); 304 struct virtio_device *vdev = vblk->vdev; 305 struct request_queue *q = vblk->disk->queue; 306 char cap_str_2[10], cap_str_10[10]; 307 u64 capacity, size; 308 309 /* Host must always specify the capacity. */ 310 vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity), 311 &capacity, sizeof(capacity)); 312 313 /* If capacity is too big, truncate with warning. */ 314 if ((sector_t)capacity != capacity) { 315 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n", 316 (unsigned long long)capacity); 317 capacity = (sector_t)-1; 318 } 319 320 size = capacity * queue_logical_block_size(q); 321 string_get_size(size, STRING_UNITS_2, cap_str_2, sizeof(cap_str_2)); 322 string_get_size(size, STRING_UNITS_10, cap_str_10, sizeof(cap_str_10)); 323 324 dev_notice(&vdev->dev, 325 "new size: %llu %d-byte logical blocks (%s/%s)\n", 326 (unsigned long long)capacity, 327 queue_logical_block_size(q), 328 cap_str_10, cap_str_2); 329 330 set_capacity(vblk->disk, capacity); 331 } 332 333 static void virtblk_config_changed(struct virtio_device *vdev) 334 { 335 struct virtio_blk *vblk = vdev->priv; 336 337 queue_work(virtblk_wq, &vblk->config_work); 338 } 339 340 static int __devinit virtblk_probe(struct virtio_device *vdev) 341 { 342 struct virtio_blk *vblk; 343 struct request_queue *q; 344 int err; 345 u64 cap; 346 u32 v, blk_size, sg_elems, opt_io_size; 347 u16 min_io_size; 348 u8 physical_block_exp, alignment_offset; 349 350 if (index_to_minor(index) >= 1 << MINORBITS) 351 return -ENOSPC; 352 353 /* We need to know how many segments before we allocate. */ 354 err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX, 355 offsetof(struct virtio_blk_config, seg_max), 356 &sg_elems); 357 358 /* We need at least one SG element, whatever they say. */ 359 if (err || !sg_elems) 360 sg_elems = 1; 361 362 /* We need an extra sg elements at head and tail. */ 363 sg_elems += 2; 364 vdev->priv = vblk = kmalloc(sizeof(*vblk) + 365 sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL); 366 if (!vblk) { 367 err = -ENOMEM; 368 goto out; 369 } 370 371 INIT_LIST_HEAD(&vblk->reqs); 372 spin_lock_init(&vblk->lock); 373 vblk->vdev = vdev; 374 vblk->sg_elems = sg_elems; 375 sg_init_table(vblk->sg, vblk->sg_elems); 376 INIT_WORK(&vblk->config_work, virtblk_config_changed_work); 377 378 /* We expect one virtqueue, for output. */ 379 vblk->vq = virtio_find_single_vq(vdev, blk_done, "requests"); 380 if (IS_ERR(vblk->vq)) { 381 err = PTR_ERR(vblk->vq); 382 goto out_free_vblk; 383 } 384 385 vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req)); 386 if (!vblk->pool) { 387 err = -ENOMEM; 388 goto out_free_vq; 389 } 390 391 /* FIXME: How many partitions? How long is a piece of string? */ 392 vblk->disk = alloc_disk(1 << PART_BITS); 393 if (!vblk->disk) { 394 err = -ENOMEM; 395 goto out_mempool; 396 } 397 398 q = vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock); 399 if (!q) { 400 err = -ENOMEM; 401 goto out_put_disk; 402 } 403 404 q->queuedata = vblk; 405 406 if (index < 26) { 407 sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26); 408 } else if (index < (26 + 1) * 26) { 409 sprintf(vblk->disk->disk_name, "vd%c%c", 410 'a' + index / 26 - 1, 'a' + index % 26); 411 } else { 412 const unsigned int m1 = (index / 26 - 1) / 26 - 1; 413 const unsigned int m2 = (index / 26 - 1) % 26; 414 const unsigned int m3 = index % 26; 415 sprintf(vblk->disk->disk_name, "vd%c%c%c", 416 'a' + m1, 'a' + m2, 'a' + m3); 417 } 418 419 vblk->disk->major = major; 420 vblk->disk->first_minor = index_to_minor(index); 421 vblk->disk->private_data = vblk; 422 vblk->disk->fops = &virtblk_fops; 423 vblk->disk->driverfs_dev = &vdev->dev; 424 index++; 425 426 /* configure queue flush support */ 427 if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH)) 428 blk_queue_flush(q, REQ_FLUSH); 429 430 /* If disk is read-only in the host, the guest should obey */ 431 if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO)) 432 set_disk_ro(vblk->disk, 1); 433 434 /* Host must always specify the capacity. */ 435 vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity), 436 &cap, sizeof(cap)); 437 438 /* If capacity is too big, truncate with warning. */ 439 if ((sector_t)cap != cap) { 440 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n", 441 (unsigned long long)cap); 442 cap = (sector_t)-1; 443 } 444 set_capacity(vblk->disk, cap); 445 446 /* We can handle whatever the host told us to handle. */ 447 blk_queue_max_segments(q, vblk->sg_elems-2); 448 449 /* No need to bounce any requests */ 450 blk_queue_bounce_limit(q, BLK_BOUNCE_ANY); 451 452 /* No real sector limit. */ 453 blk_queue_max_hw_sectors(q, -1U); 454 455 /* Host can optionally specify maximum segment size and number of 456 * segments. */ 457 err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX, 458 offsetof(struct virtio_blk_config, size_max), 459 &v); 460 if (!err) 461 blk_queue_max_segment_size(q, v); 462 else 463 blk_queue_max_segment_size(q, -1U); 464 465 /* Host can optionally specify the block size of the device */ 466 err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE, 467 offsetof(struct virtio_blk_config, blk_size), 468 &blk_size); 469 if (!err) 470 blk_queue_logical_block_size(q, blk_size); 471 else 472 blk_size = queue_logical_block_size(q); 473 474 /* Use topology information if available */ 475 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 476 offsetof(struct virtio_blk_config, physical_block_exp), 477 &physical_block_exp); 478 if (!err && physical_block_exp) 479 blk_queue_physical_block_size(q, 480 blk_size * (1 << physical_block_exp)); 481 482 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 483 offsetof(struct virtio_blk_config, alignment_offset), 484 &alignment_offset); 485 if (!err && alignment_offset) 486 blk_queue_alignment_offset(q, blk_size * alignment_offset); 487 488 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 489 offsetof(struct virtio_blk_config, min_io_size), 490 &min_io_size); 491 if (!err && min_io_size) 492 blk_queue_io_min(q, blk_size * min_io_size); 493 494 err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY, 495 offsetof(struct virtio_blk_config, opt_io_size), 496 &opt_io_size); 497 if (!err && opt_io_size) 498 blk_queue_io_opt(q, blk_size * opt_io_size); 499 500 501 add_disk(vblk->disk); 502 err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial); 503 if (err) 504 goto out_del_disk; 505 506 return 0; 507 508 out_del_disk: 509 del_gendisk(vblk->disk); 510 blk_cleanup_queue(vblk->disk->queue); 511 out_put_disk: 512 put_disk(vblk->disk); 513 out_mempool: 514 mempool_destroy(vblk->pool); 515 out_free_vq: 516 vdev->config->del_vqs(vdev); 517 out_free_vblk: 518 kfree(vblk); 519 out: 520 return err; 521 } 522 523 static void __devexit virtblk_remove(struct virtio_device *vdev) 524 { 525 struct virtio_blk *vblk = vdev->priv; 526 527 flush_work(&vblk->config_work); 528 529 /* Nothing should be pending. */ 530 BUG_ON(!list_empty(&vblk->reqs)); 531 532 /* Stop all the virtqueues. */ 533 vdev->config->reset(vdev); 534 535 del_gendisk(vblk->disk); 536 blk_cleanup_queue(vblk->disk->queue); 537 put_disk(vblk->disk); 538 mempool_destroy(vblk->pool); 539 vdev->config->del_vqs(vdev); 540 kfree(vblk); 541 } 542 543 static const struct virtio_device_id id_table[] = { 544 { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID }, 545 { 0 }, 546 }; 547 548 static unsigned int features[] = { 549 VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY, 550 VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI, 551 VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY 552 }; 553 554 /* 555 * virtio_blk causes spurious section mismatch warning by 556 * simultaneously referring to a __devinit and a __devexit function. 557 * Use __refdata to avoid this warning. 558 */ 559 static struct virtio_driver __refdata virtio_blk = { 560 .feature_table = features, 561 .feature_table_size = ARRAY_SIZE(features), 562 .driver.name = KBUILD_MODNAME, 563 .driver.owner = THIS_MODULE, 564 .id_table = id_table, 565 .probe = virtblk_probe, 566 .remove = __devexit_p(virtblk_remove), 567 .config_changed = virtblk_config_changed, 568 }; 569 570 static int __init init(void) 571 { 572 int error; 573 574 virtblk_wq = alloc_workqueue("virtio-blk", 0, 0); 575 if (!virtblk_wq) 576 return -ENOMEM; 577 578 major = register_blkdev(0, "virtblk"); 579 if (major < 0) { 580 error = major; 581 goto out_destroy_workqueue; 582 } 583 584 error = register_virtio_driver(&virtio_blk); 585 if (error) 586 goto out_unregister_blkdev; 587 return 0; 588 589 out_unregister_blkdev: 590 unregister_blkdev(major, "virtblk"); 591 out_destroy_workqueue: 592 destroy_workqueue(virtblk_wq); 593 return error; 594 } 595 596 static void __exit fini(void) 597 { 598 unregister_blkdev(major, "virtblk"); 599 unregister_virtio_driver(&virtio_blk); 600 destroy_workqueue(virtblk_wq); 601 } 602 module_init(init); 603 module_exit(fini); 604 605 MODULE_DEVICE_TABLE(virtio, id_table); 606 MODULE_DESCRIPTION("Virtio block driver"); 607 MODULE_LICENSE("GPL"); 608